But despite the lack of actual weapons, the White House said the report showed Saddam Hussein's intent and capability and justifies the decision to go to war.

Democrats, on the other hand, used the report to attack the Bush administration, claiming the president misled the American people.

UK Prime Minister Tony Blair said that while he now accepted that Iraq held no stockpiles of WMD ready to be deployed at the time of the invasion, the report showed that UN sanctions had not been working.

Key findings in the report:

"The ISG has not found evidence that Saddam possessed WMD stocks in 2003, but [there is] the possibility that some weapons existed in Iraq, although not of a militarily significant capability."

"There is an extensive, yet fragmentary and circumstantial body of evidence suggesting that Saddam pursued a strategy to maintain a capability to return to WMD after sanctions were lifted... "

"The problem of discerning WMD in Iraq is highlighted by the pre-war misapprehensions of weapons which were not there. Distant technical analysts mistakenly identified evidence and drew incorrect conclusions."

'Unaffordable risk'

The ISG also published a list of people and groups to whom Saddam Hussein allegedly offered cheap oil in return for their support in trying to get UN sanctions lifted.

Many on the list - drawn from official Iraqi documents - are from Russia, France and China - countries which opposed the war in Iraq.

HAVE YOUR SAY

Saddam Hussein may be guilty of a number of dreadful things, but thought crime - is this a new legal precedent?

The BBC's Adam Brookes in Washington says the report will be used by both sides in the US election race - while laying to rest the myth of WMDs it will inflame the argument over whether Iraq under Saddam Hussein constituted a true threat.

President Bush again defended last year's invasion, though he made no reference to the report.

He told supporters on his election campaign trail that the world was better off without Saddam Hussein, and the risk of him passing weapons of mass destruction (WMD) to terror groups was "a risk we could not afford to take".

But the top Democrat on the Armed Services Committee, Senator Carl Levin, said
Mr Duelfer's findings undercut the government's main arguments for war.

"We did not go to war because Saddam had future intentions to obtain weapons of mass destruction," Mr Levin said.

High political stakes

Mr Blair said the report showed that Saddam Hussein had planned to develop WMD.

IRAQ SURVEY GROUP

Set up in May 2003

First leader, David Kay, quit in Jan 2004 stating WMD would not be found in Iraq

"I welcome the report because I think it will show us that it is far more of a complicated situation than people thought," he told reporters during a trip to Ethiopia.

Iraq's Deputy Prime Minister, Barhem Saleh, said anyone who doubted that Saddam Hussein had WMDs only needed to visit Halabja - where the former Iraq dictator had gassed thousands of Kurds.

But former chief UN weapons inspector Hans Blix said he hoped Mr Blair and Mr Bush would now admit that the invasion of Iraq was a mistake.

"Had we had a few months more [of
inspections before the war], we would have been able to
tell both the CIA and others that there were no weapons of
mass destruction [at] all the sites that they had given to
us," he said, quoted by the Associated Press news agency.

The ISG's verdict has been widely anticipated since the former head of the group, David Kay, resigned in January, and following the leaking of a draft copy of the report last month.

The group plans to continue translating and evaluating an estimated 10,000 boxes of documents seized in Iraq.